"Being a b**** wasn't hard for me at all!", she told this month's Empire magazine.

"Okay, I take it back - that's the stuff you dream of doing.

"That's like getting to eat cake every day - especially having a director like Jason saying, 'Yeah, more of that!'."

Charlize said the role, as a writer of teen literature who heads back to her hometown in a bid to win back her now-married high school boyfriend, made a change from previous films.

"I'm so not a dark person, but I end up doing these movies that are horrific, and I swear to God I feel like producers in Hollywood are like, 'Oh, does she get raped and cry? Send it to Charlize!'," the Monster star said.